St. Petersburg, Florida - He hasn't answered any questions. He won't give a DNA sample. And, he was the last person to see missing police cadet Kelly Rothwell alive.

David Perry was Kelly's boyfriend, but fled to New York shortly after her disappearance. The question is why.

He was 11 years older than her and very controlling in their relationship. Kelly was a former human resources administrator who then switched careers and entered the police academy in November 2010.

She felt empowered, so empowered that she was on her way to break up with him nearly two weeks ago. She hasn't been seen since.

Did Perry have something to do with it? Why won't he talk? If he isn't guilty, why won't he commit to a DNA sample?

So many questions, but there are very few answers at this point. Pinellas investigators find the case frustrating.

Pinellas Detective Amy Plourde tells us, "It tears at you, I want to find Kelly. I want to find her to give the family peace, I also want to find her because she doesn't deserve to be somewhere hurt or in pain out there by herself."

Detectives tell us that Perry came back to Florida on Sunday and was cleaning out a storage unit.

But, they would not confirm what was he was removing from the unit. 10 News asked to look at the surveillance footage, they would not reveal it.

"He looked like he hadn't slept or eaten in several days, frazzled looking. He was nervous, absolutely he was nervous, but I don't know if he was scared or not," said Detective Mike Bailey.

Detectives are playing this case very carefully when releasing information. For example, when we asked if they were trailing Perry, and watching his every move, they simply smiled and said we can't answer that question.

Detective Plourde added, "I think it's been in his brain that he's been watched for some time now... He's a smart guy. It wouldn't surprise me that he would say that people have had eyes on him for a few days now."

Former prosecutor Erin Wolfe says the detectives have a tough case to crack, but she says the intense media attention can help.

Wolfe said, "Can cases be prosecuted without a dead body? Of course they can. Have they been successfully prosecuted without a body, yes they have. But, it's an extremely difficult hurdle to overcome."

Now, all detectives can do is wait.

They served a search warrant on her condo, looking for everything from hair fibers to cell phones. They also served a warrant on his car in New York.

"I don't know if the walls closing in is a good analogy, but something close to that. I think he feels he doesn't feel that he has a whole lot of avenues to go to right now. I feel like he's kind of in a corner," says Plourde.